Molecular self-assembly is the spontaneous association of molecules under equilibrium conditions into stable, structurally well-defined aggregates joined by noncovalent bonds. Molecular self-assembly is ubiquitous in biological systems and underlies the formation of a wide variety of complex biological structures. Understanding self-assembly and the associated noncovalent interactions that connect complementary interacting molecular surfaces in biological aggregates is a central concern in structural biochemistry. Self-assembly is also emerging as a new strategy in chemical synthesis, with the potential of generating nonbiological structures with dimensions of 1 to 10(2) nanometers (with molecular weights of 10(4) to 10(10) daltons). Structures in the upper part of this range of sizes are presently inaccessible through chemical synthesis, and the ability to prepare them would open a route to structures comparable in size (and perhaps complementary in function) to those that can be prepared by microlithography and other techniques of microfabrication.

Molecular self-assembly and nanochemistry: A chemical strategy for the synthesis of nanostructures

In the past decade, mesoporous silica nanoparticles (MSNs) have attracted more and more attention for their potential biomedical applications. With their tailored mesoporous structure and high surface area, MSNs as drug delivery systems (DDSs) show significant advantages over traditional drug nanocarriers. In this review, we overview the recent progress in the synthesis of MSNs for drug delivery applications. First, we provide an overview of synthesis strategies for fabricating ordered MSNs and hollow/rattle-type MSNs. Then, the in vitro and in vivo biocompatibility and biotranslocation of MSNs are discussed in relation to their chemophysical properties including particle size, surface properties, shape, and structure. The review also highlights the significant achievements in drug delivery using mesoporous silica nanoparticles and their multifunctional counterparts as drug carriers. In particular, the biological barriers for nano-based targeted cancer therapy and MSN-based targeting strategies are discussed. We conclude with our personal perspectives on the directions in which future work in this field might be focused.

Mesoporous Silica Nanoparticles: Synthesis, Biocompatibility and Drug Delivery

A mean-field phase diagram for conformationally symmetric diblock melts using the standard Gaussian polymer model is presented. Our calculation, which traverses the weak- to strong-segregation regimes, is free of traditional approximations. Regions of stability are determined for disordered (DIS) melts and for ordered structures including lamellae (L), hexagonally packed cylinders (H), body-centered cubic spheres (QIm3m), close-packed spheres (CPS), and the bicontinuous cubic network with Ia3d symmetry (QIa3d). The CPS phase exists in narrow regions along the order−disorder transition for χN ≥ 17.67. Results suggest that the QIa3d phase is not stable above χN ∼ 60. Along the L/QIa3d phase boundaries, a hexagonally perforated lamellar (HPL) phase is found to be nearly stable. Our results for the bicontinuous Pn3m cubic (QPn3m) phase, known as the OBDD, indicate that it is an unstable structure in diblock melts. Earlier approximation schemes used to examine mean-field behavior are reviewed, and compa...

Unifying Weak- and Strong-Segregation Block Copolymer Theories

Good control of the morphology, particle size, uniformity and dispersity of mesoporous silica nanoparticles (MSNs) is of increasing importance to their use in catalyst, adsorption, polymer filler, optical devices, bio-imaging, drug delivery, and biomedical applications. This review discusses different synthesis methodologies to prepare well-dispersed MSNs and hollow silica nanoparticles (HSNs) with tunable dimensions ranging from a few to hundreds of nanometers of different mesostructures. The methods include fast self-assembly, soft and hard templating, a modified Stober method, dissolving–reconstruction and modified aerogel approaches. In practical applications, the MSNs prepared by these methods demonstrate good potential for use in high-performance catalysis, antireflection coating, transparent polymer–MSNs nanocomposites, drug-release and theranostic systems.

Synthesis of mesoporous silica nanoparticles

Large-Scale Fabrication of Boron Nitride Nanosheets and Their Utilization in Polymeric Composites with Improved Thermal and Mechanical Properties

The present invention discloses a strong lipophilic long chain Alpha-olefin amphiphilic graft copolymer and a preparation method thereof. The present invention takes a long chain Alpha-olefin-p-methylstyrene copolymer as the matrix; the polyethylene glycol with one hydroxyl terminal is grafted on the chain of the copolymer by a bromination reaction and an etherification reaction. A molecular structure (such as the grafting density and graft length) of the graft copolymer can be effectively controlled by the method. The preparation method of the strong lipophilic long chain Alpha-olefin amphiphilic graft copolymer which is related by the present invention has simple process and convenient operation, the graft copolymer can be fully dissolved in the non-polar solvent (such as, n-octane, petrol, diesel, etc.) under the room temperature, the present invention has the broad application prospect in emulsible oil, cosmetics, inverse emulsion polymerization, non-polar membrane surface modification and other fields.

Strong-hydrophobicity long chain alpha-olefin amphiphilic graft copolymer

Glassy polymer nanofibers with spatially confined poly(ethylene oxide) (PEO) were fabricated by coaxial electrospinning of PEO with polyacrylonitrile (PAN) or polystyrene. The effect of melt-annealing on the crystallization behavior of the confined PEOs was studied using differential scanning calorimetry. It is found that the crystallization behavior of the confined PEOs varies with annealing temperature (Ta), annealing time (ta), and molecular weight of PEO. Notably, it is observed that the crystallization temperature (Tc) and melting temperature (Tm) of PEO increase with prolongation of ta, for PEO600K/PAN and PEO2K/PAN coaxial electrospun fibers. This phenomenon can be interpreted by the annealing-induced demixing at the core-sheath interface. After the coaxial electrospinning, the core and sheath of the PEO/PAN coaxial fibers are partially compatible due to the miscible solvents used for the core and sheath polymers. Upon annealing, demixing occurs at the core-sheath interface, leading to improved crystallizability of PEO. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45760.

Effect of annealing-induced interfacial demixing on crystallization of PEO confined in coaxial electrospun nanofibers

The invention discloses a hydrophilic modifier for polyethylene films and a preparation method thereof. The invention is characterized by using a long-chain alpha-olefin-tert butyl acrylate copolymer as a matrix and grafting polyethylene glycol with hydroxyl at one terminal onto a copolymer chain through hydrolysis and esterification. Such molecular structures as graft density and branched chain length of the graft copolymer can be effectively controlled through the method. The method is simple in process and convenient to operate. The hydrophilicity of the surfaces of the polyethylene films can be substantially improved by coating the modifier on the surfaces of the polyethylene films, and the modifier is firmly jointed with the polyethylene films and is not easy to run off because of being scoured by water. The hydrophilic modifier can be used for preparing long-acting antifogging polyethylene films.

Hydrophilic modifier for polyethylene films and preparation method thereof

Polymerization of vinyl chloride catalyzed by a titanium complex with an anionic oxygen tripod ligand

A series of linear amphiphilic pentablock terpolymer PAAx-b-PS48-b-PEO46-b-PS48-b-PAAx (AxS48O46S48Ax) with various lengths x of the PAA block (x = 15, 40, 60, and 90) were synthesized via a two-step atom transfer radical polymerization (ATRP) using Br-poly(ethylene oxide)-Br (Br-PEO46-Br) as the macroinitiator, styrene (St) as the first monomer, and tert-butyl acrylate (tBA) as the second monomer, followed with the hydrolysis of PtBA blocks. The AxS48O46S48Ax pentablock terpolymers formed micelles in dilute aqueous solution, of which the morphologies were dependent on the length x of the PAA block. Cryogenic transmission electron microscopy (cryo-TEM), dynamic light scattering (DLS), and zeta potential measurement were employed to investigate the morphologies, chain structures, size, and size distribution of the obtained micelles. The morphology of AxS48O46S48Ax micelles changed from spherical vesicles with ordered porous membranes to long double nanotubes, then to long nanotubes with inner modulated nanotubes or short nanotubes, and finally, to spherical micelles or large compound vesicles with spherical micelles inside when x increased from 15 to 90. The hydrophobic PS blocks formed the walls of vesicles and nanotubes as well as the core of spherical micelles. The hydrophilic PEO and PAA block chains were located on the surfaces of vesicle membranes, nanotubes, and spherical micelles. The PAA block chains were partially ionized, leading to the negative zeta potential of AxS48O46S48Ax micelles in dilute aqueous solutions.

https://www.mdpi.com/2073-4360/12/10/2183/pdf

Jun-Ting Xu

Papers

Strong-hydrophobicity long chain alpha-olefin amphiphilic graft copolymer

Effect of annealing-induced interfacial demixing on crystallization of PEO confined in coaxial electrospun nanofibers

Hydrophilic modifier for polyethylene films and preparation method thereof

Polymerization of vinyl chloride catalyzed by a titanium complex with an anionic oxygen tripod ligand

Self-Assembly of Linear Amphiphilic Pentablock Terpolymer PAAx-PS48-PEO46-PS48-PAAxin Dilute Aqueous Solution.